Demands on the electrical transmission and distribution system continue to increase. Disturbances in the electrical power grid cause social and economic hardship. As a result, scrutiny on the electrical power grid and its management have increased. Means are continuously being sought to improve management of the electrical power grid. One way to achieve a more reliable power grid is through more accurate identification of events and disturbances.
SNTP is a communication protocol that is widely used in digital communication systems. It is a simplified derivation of Network Time Protocol (NTP), which is an Internet protocol used to synchronize the clocks of computers. Particular versions of SNTP are referred to as Request For Comments (RFC) versions. Some examples of RFC versions of SNTP include RFC 2030, RFC 1769, and RFC 1361.
IEC 61850 is an international standard for substation automation systems which defines communication between devices, such as Intelligent Electronic Devices (IED's), in a substation and related system requirements. IEC-61850-8-1 is part 8-1 (Specific Communication Service Mapping) of the IEC 61850 standard, which specifies utilization of SNTP RFC 2030 for time synchronization of IED's in substations. In a modern electrical substation IEC-61850-8-1 is typically used for communication between IED's both vertically and horizontally. IEC-61850-8-1 uses SNTP for synchronization purposes and a good synchronization in the IED is of utmost importance for event handling and disturbance-handling.
SNTP provides a “Ping-Pong” method of synchronization. Along these lines, a message is typically sent from an IED to a time-provider. The time-provider typically returns the message after filling in a reception time and a transmission time. Typically, SNTP provides a synchronization-level of about 10 ms.